In general, the invention relates to parathyroid hormone (PTH) analogs, particularly those having long-acting agonist activity at the PTH receptor. These analogs can be used to treat diseases where long-acting activity is desirable, such as hypoparathyroidism.
PTH(1-34) (SEQ ID NO:10) is an effective therapeutic in treatment of osteoporosis and conditions of PTH deficiency, namely hypoparathyroidism. Hypoparathyroidism is a life-long disease characterized by an inadequate production of parathyroid hormone (PTH) by the parathyroid glands. Because PTH is critical for regulation of calcium and phosphate levels, loss of PTH reduces calcium levels in blood and bones and increases phosphate levels (hypocalcemia and hyperphosphatemia). Hypocalcemia leads to symptoms such as neuromuscular irritability, including paresthesias, muscle twitching, laryngeal spasms (which can lead to inability to speak and to alert health providers to the underlying medical condition, which has led to delayed or incorrect treatment), and possibly tetany and seizures. It is the only endocrine disorder in which the missing hormone (namely PTH) is not yet available as therapy.
PTH(1-34) (SEQ ID NO:10) has been identified as a safe and effective alternative to calcitriol therapy for hypoparathyroidism and is able to maintain normal serum calcium levels without hypercalciuria (Winer et al., J Clin Endocrinol Metab 88:4214-4220, 2003). Nonetheless, the polypeptide requires injection at least twice daily, and the need in this disease for a long-acting PTH(1-34) (SEQ ID NO:10) analog has therefore been recognized (Winer et al., supra).
Thus, there exists a need for additional PTH receptor agonists, particularly those having long-acting activity at the PTH receptor.